Melanoma is a serious form of skin cancer in humans. It arises from the pigment cells (melanocytes), usually in the skin. The incidence of melanoma is increasing at the fastest rate of all cancers in the United States with a lifetime risk of 1 in 68. Although melanoma accounts for only 4% of all dermatologic cancers, it is responsible for 80% of all deaths from skin cancers. It has long been realized that recognition and diagnosis of melanoma, when it is early stage disease, is key to its cure.
Given this, it is imperative that research be carried out not only on therapeutics for melanoma, but also on all aspects of melanoma including prevention and detection. Most of these deaths from melanoma could have been prevented if the melanomas, initially located on the skin, could have been detected in their early stages. The ability to cure melanoma in its earliest skin stage, in situ, is virtually 100% if the melanoma is adequately surgically excised. If the melanoma is caught in a later stage, where it has invaded to a depth of 4 mm or more, the ten-year survival rate is less than 50%. If the melanoma is not detected until it has spread to distant parts of the body (Stage IV), the prognosis is dismal, with only 7-9% of patients surviving 5 years, with the median survival time being 8-9 months. The long-term “cure” rate for Stage IV melanoma is only 1-2%.
To advance early detection of melanoma, several things must be improved. People need to be better educated with regards to the risks of melanoma and how to prevent and detect it on their own skin. Also physicians need to be more alert to the possibility of melanoma and be better trained in detection. But even if these two areas are improved, the diagnosis of melanoma on the skin is still difficult. Studies have shown that even expert clinicians working in pigmented lesion clinics where melanoma is their specialty are only able to determine whether a suspicious pigmented lesion is melanoma or not with 60-80% sensitivity. This leads to the need for surgical biopsy of large numbers of pigmented lesions for every melanoma that is detected, and, doubtless, to the missing of some melanomas in their early stages.
In current practice melanoma is diagnosed by biopsy and histopathological examination; approximately 20 to 30 biopsies must be performed to find one melanoma and even then some melanomas are missed in the earliest stage. The limitations of visual detection are apparent to dermatologists who are constantly searching for ways to better determine whether suspicious lesions are melanoma or not without having to cut them out first. To this end, epiluminescence microscopy (ELM) has come into use. This is a method whereby lesions are looked at using a device that simultaneously magnifies the lesion while reducing visual interference from refractive index differences at the skin-air interface. While ELM does give a different view, it is of limited improvement. Studies have shown that until one becomes fairly skilled in utilizing the instrument, sensitivity in detection of melanoma actually decreases. Even very skilled users of ELM improve their ability to detect melanomas only by 5-10%. This still leads to an unacceptable sensitivity in detection and the need to biopsy large numbers of benign lesions to detect a few melanomas. And again, some melanomas will be missed completely in their early stages.
Clearly there is a need for further development of technology that will enable physicians to determine the nature and extent of suspicious lesions of the skin. Such technology would ideally directly assay the physiology of the suspect lesion to enable a sensitive diagnosis.